The Free Google Analytics Connector included with all Analytics Edge Add-ins for Excel, even the free Basic Add-in, includes the ability to minimize sampling problems with large sites and long time frame queries. Simply add a date dimension, then check the box to Minimize Sampling on the Options tab, and Analytics Edge will make separate queries for each date in the selected date range and merge the results into a single table. To be effective, it must be used with a Date, Week, or Month dimension.
Analytics Edge will automatically make a separate query for each time period in the query and merge the results. Since each query covers a shorter date range, the sampling error is reduced if not eliminated.
Mixed time dimensions, accurate data
Note that if you use multiple time dimensions in the query, like Date and Month of Year, Analytics Edge will make queries for the smallest — the Date in this example. You will always get the finest resolution possible, and the most accurate numbers; Analytics Edge always queries Google Analytics asking for the HIGHER_PRECISION sampling level.
How does this work?
Data sampling occurs in Google Analytics when the data you need for your report exceeds about 500,000 sessions. Google samples larger amounts of data to make the report faster (and reduce the load on their server). Analytics Edge breaks your request into separate queries with shorter time periods, then transparently joins the results together. By using the date dimensions already in your query, all of the metrics reported are accurate — there is no special handling required for average or rate metrics.